Is there any work has been done on the latest (ttbomk) proposal for impredicative types in Haskell:

> Guarded impredicative polymorphism by Alejandro Serrano, Jurriaan Hage, Dimitrios Vytiniotis, Simon Peyton Jones
https://www.microsoft.com/en-us/research/wp-content/uploads/2017/07/impredicative-Jul17.pdf